Examples of known fuel injector use an armature assembly having an armature that reciprocates between an open position and a closed position. The distance that the armature travels is known as an injector lift height, working air gap or distance. The working air gap or distance is one of many variables that determine the amount of fuel that will be dispensed outside the fuel injector when the injector is actuated.
The air gap is believed to be set by first taking a series of direct contact measurements. One direct measurement is believed to determine the distance between a contact face of a pole piece of the armature assembly and a sealing diameter of a seat. Another direct measurement is believed to determine the distance between the sealing diameter of a seat and the position of a closure member during a full open position. The difference between these two measurements determines the approximate working gap. The actual working gap is believed to be set by using a deformable ring that is inserted into a shoulder formed at one end of a valve body. The ring is subsequently crushed to the approximate working gap.
The actual working gap, however, may vary between individual injectors due to variations in the direct measurement operations, the deformability of the crush ring material or the valve body. Moreover, the direct measurements oftentimes can introduce contaminants into the fuel injector, leading to the possibility of inconsistent injector performance. Additionally, the crushing operation is believed to introduce undesirable structural loading on the body of the injector. Furthermore, the use of crush ring is believed to require random samplings of the crush ring and injectors to maintain consistent injector performance. Finally, once the crush ring is installed or crushed, it is believed that no adjustment can be made unless the crush ring is extracted and replaced with a new one.